It's a frightening thought (in some ways) to think that the universe is completely indifferent to our fate (as it is indifferent to life itself, in fact indifferent to everything).
It is much more comforting to think that there is some authority, a higher force, a benevolent God (or whatever you want to imagine) watching over us, morally guiding us, helping us. We are but children without parents in this universe. It is easy to see the powerful attraction of this thinking. It devolves responsibility for the terrible things that go on in this world. It gives some simple meaning to our lives and promises possible rewards at the end (if we abide by whatever set of rules our culture/religion dictates). It gives people identity, a simple way of labeling their lives and gives structure to their lives. It gives optimism and certainty in an uncertain world.
The problem is, this belief requires rejecting truth, evidence, facts. It requires faith - that unquestioning belief in something, unquestioning belief in anything no matter how absurd. It is this that is so dangerous.
Of course, most people are not so stupid as to believe anything despite the evidence to the contrary, so their beliefs have evolved, been compromised, twisted in all directions until they make even less sense, but people resist ditching it altogether because they do not want to confront the ultimate truth - that it is up to humanity to improve humanity, we cannot rely on some imaginary outside force to do it for us.
This post was inspired by this survey (courtesy of our Conservative Humanist friend) which shows a majority of people still believing absurd things. The only good thing for the future is that religious belief is lower amongst the younger generations.